The present disclosure relates to a back irradiation type solid-state imaging device, a manufacturing method thereof, and electronic equipment using the solid-state imaging device.
In the past, as a solid-state imaging device which is used in a digital camera or a video camera, a CCD type solid-state imaging device or a CMOS type solid-state imaging device has been known. In these solid-state imaging devices, a light sensing section is formed for each pixel of a plurality of pixels formed in a two-dimensional matrix form, and in the light sensing section, a signal charge is produced depending on the amount of received light. Then, the signal charge produced in the light sensing section is transmitted and amplified, whereby an image signal is obtained.
Further, in recent years, a back irradiation type solid-state imaging device has been proposed which is irradiated with light from the opposite side to the side on a substrate on which a wiring layer is formed. In the back irradiation type solid-state imaging device, since a wiring layer, a circuit element, or the like is not provided on the light irradiation side, the aperture ratio of the light sensing section formed in a substrate can be increased and in addition, since incident light is incident on the light sensing section without being reflected by the wiring layer or the like, improvement in sensitivity can be attained.
Incidentally, in the back irradiation type solid-state imaging device, in order to draw out an electrode pad of the wiring layer formed on the surface side of the substrate to the back side that is the light irradiation side of the substrate, a through-hole which penetrates the substrate from the light irradiation surface of the substrate and exposes the electrode pad is formed. In manufacturing methods of a solid-state imaging device in the past, such a through-hole is formed after or before formation of an on-chip lens which is formed on the light incidence plane side of the substrate.
In Japanese Unexamined Patent Application Publication No. 2005-285814, in the back irradiation type solid-state imaging device, a configuration is described in which an on-chip lens is formed after formation of the through-hole in which the electrode pad is exposed. In this manner, in a case where the on-chip lens is formed after formation of the through-hole, there is a problem in that application unevenness of a resist material at the time of formation of the on-chip lens is generated due to the influence of the through-hole, so that the shape of the on-chip lens becomes non-uniform in a plane. In a case where the shape of the on-chip lens is non-uniform, there is concern that variation in light condensing characteristic may be generated in a chip.
Further, in a case where an electrode layer is formed on the back side of the substrate after formation of the on-chip lens, the probability of a change in the shape of the on-chip lens due to patterning of the electrode layer, or cohesion of scattering particle constituents due to a difference in etching of the electrode layer onto the on-chip lens is high. For this reason, in a case where the electrode layer is formed on the back side of the substrate after formation of the on-chip lens, there is concern that a defect due to the particle constituents may be generated.
Further, as in Japanese Unexamined Patent Application Publication No. 2005-285814, in a case where from the back side of the substrate, a bonding wire is connected to the electrode pad formed on the surface side of the substrate, it is necessary to insert the bonding wire into the through-hole which penetrates the substrate. For this reason, connection to an external terminal by the bonding wire is difficult, so that there is concern that yield at the time of assembly may be reduced.